Rotary drilling tool



DCC 22, 1931- F. o. WADSWORTH 1,838,067

ROTARY DRILLING TOOL Original Filed March l0, 1921 HIS ATTORNEYS Patented Dec. 22, 1931 FRANK L. O. WADSWORTH, OF PITTSBURGH, PENNSYLVANIA ROTARY DRILLING TOOL Original application led March 10, 1921, Serial No. 1927. serial This invention relates in general to rotary boring tools which utilize a plurality of revolvable cutters to perform the drilling operation, and has for an object the provision of a means for continuously lubricating the bearings of the cutter members, which is actuated and controlled by the movement of those members, and is in no way affected by the pressure, or the rate of flow, of the liquid that is used in iiushing out and carrying away the excavated material. One of the advantages of this feature of improvement lis that the rate of feed of the lubricant may be preadjusted to the rate of movement of the revolving cutters, and this predetermined ratio may be automatically maintained under all conditions of operation. This application is a division of my copending application Serial No. 451,223, filed March 10, 1921.

Other objects and advantages of my invention will be developed more fullyby the consideration of the three illustrative embodiments thereof, which are shown in the accompanying drawings; in which:

Figure 1 is a partial side elevation of a drill head, the lower part of which is shown in half section on the plane l--I of Fig. 2, while the upper portion is correspondingly sectional on the central plane 63-6C of that' figure. Fig. 2 is a sectional plan view on the plane HI of Figs. 1 and 3. Fig. 3 is a longitudinal section, partly in elevation, on the plane Ill-IH of Fig. 2. Fig. l is a longitudinal central section-as on the plane IV--IV of Fig. -iof a second illustrative form of my improved boring tool. Fig. 5 is a sectional view onv the two plane level V-V of Fig. 4l. Fig. 6 is a sectional elevation on the plane VI-VI of Fig. 5.

In the construction shown in Figs. 1, 2 and 3, the head of the tool is made in two sections;

'-a lower section 12a, which carries the four complementary cutter `members 13a-13a, 14a-14a; and an upper tubular section 15,

which is screwed thereon, and which is threaded at its top to receive the end of the driving drill stem 16a'. The cutters 13DL are revolvably mounted on inwardly inclined stud* shafts 17a, which are symmetrically offset with respeot to the longitudinal axis C--C of the 451,223. Divided and this application led May 5,

drill head; and the cutters 1413-14a are secured to, or are integral with, vertically dis-` posed shafts 18a, 18a which are journaled in the split bushings 27a, 27a that are detachably secured in the head by the screws 65, 65, etc. The cutters l13a are held in position on the coned stud Ishafts 17a by means of the split ianged bushings 66, that are clamped to the cutters by the screws 67 and the stud shafts themselves are rigidly locked in their supporting sockets on the head by the screws 24a-24a,

Vthe heads of which are preferably covered with fusible metal seals 26a, 26a. Each of the vertical cutter shafts 18a is also provided with an extension shaft 68, which has an enlarged head 70 that engages the top of the split bushings 27a, and which carries, at its upper end, a screw collar 71 that co-operates with the parts 27a and 70 in preventing any accidental removal ofthe cutter member 14a-48a.

rEach of the offset cutters 13a is preferably of hyper-conoidic'form, and is provided with an elliptically rounded end rib, a. These rounded ends engage with the boundary zone between the bottom and the completed side wall of the borehole; butin this case the said engagement is confined to a very narrow annulus by the inward inclination of the axes and end surfaces of the rolling cutters. The duty imposed on the tooth elements of the ribs 20 is therefore relatively light even when no complementaryl cutters are employed; but for the purpose of relieving these tooth elements of substantially all shearing action,`I arrange the vertical spindle cutters, 14, in such relationship to the head that the peripheral teeth thereonroll on the parallel sides ofthe bore cavity and cut away the material from the path of the rotating and revolving edges 20a, 20a. The latterk then serve only asV guard elements, or as auxiliary supplemental elements, that may co-operate with the lower edge portions of the toothed cutters 14a, when the latter become somewhat worn, orwhen -they encounter extremely hard strata of material.

This exemplification of my invention is also provided with devices which are adapted to feed a continuous supply of lubricant to the bearings of the revolving cutters, and which are automatically actuated and controlled by the cutter movement itself. In the form here shown this automatic feeding means comprises a small short stroke plunger pump 72 the piston of which is actuated by an eccentric pin 7 3 in one extension `shaft collar 71. rlhe action of thepump draws oil through aflap valve controlled port 7 2* from the lower portion of theannular lubricant chamberwhich is formed by the upper section l5 of the head and the central water tube conduit 341--and forces it into an annular groove, -7 4, that is covered by the flanged collar v'35a at the lower end of the saidVV tube 34a. The annular passage way 74 is in communication vwith the journal bearings of the hyperconoidic rolling cutters 13a through the ducts 393-40 (see `Fig. l) and is also connected with the bearing surfaces` of the shafts 16a by means of the passage ways 57, 57a (see Fig. 3); andthe oilwhich is pumped into the covered groove is therefore uniformly distributed to thefvarious cutter bearings at a rate which is determined by the relative areas of the differ-ent ducts and the angular velocity of the revolving members.

The upper surface of the mass of lubricant in the annular reservoir is covered and protected by a light piston member 41, which r gradually ydescends as the oil is pumped out from the bottom of the chamber.V In this construction the space'above the descending pistonis vin open ycommunication with the fluid which surrounds lthe drill head through the opening, or openings, 75. The hydrostatic pressure onthe oppositeends ofthe lubricant column is thus normally balanced; and the action of the oil feed pump 72 is, therefore, not affected 4by changes, either inthe absolute pressures, or in the differential pressures, of the fiushing liquid insideV and outside the drill stem.

The vflushing liquid is carried downthrough the central tube 343-, and is directed tangentially downward, on the rearward and upwardly moving sides of :the rolling cutters 13a-43, through the inclined passage ways 383-3851. This arrangement results in the discharge of the streams of liquid at the points where their velocities aregreatest with respect to the 'cutter Asurfaces'on which they impinge; and thus effects a rapid and effective rcleaning of thel tooth elements of the skew rolling bits `as they leave the material on which they are operating. The utilization of this feature of my improved construction is particularly advantageous inthe case of such an organization as that last described,'in which the greater part of the drilling operation is performed by two offset lhyper-conoidic cutting rollers that remove the material 'from the bottom ofthe bore hole by a rcombined curtate-cycloidic chipping action and a side wedging or vend thrust movement of'their skew tooth elements; and in which there is, therefore, a tendency to wedge a considerable amount of loose material into the grooves of the toothed surfaces.

Figs. 4, 5 and 6 illustrates another embodiment of my present invention, in which Ithe drill head is, as before, preferably constructed in two sections 12b and 15", that are detachably locked together by a screw joint, and are adapted to be secured tothe lower end of the threaded vdrillstem 1Gb in the usual The lower section 12b carries two coned cutter rollers, lSL-l", that are mounted on inclined studrpins 17h, each of which is Ypreferably made-integral with a block 7 6 (as shown in detail in Fig. 6). These cone cutters'are revolvably secured on their stud pin supports by means of the split flanged bushings 77, that are held in place in the hub of the cutters by clamp screws 78; and the block supports 76-76 are rigidly clamped in milled grooves on the opposite sides of the head by the cross bolts 24h-24". The member 12b also carries two complementary side cutting rollers 14h-14", which are journalled on shafts 18h-18b that are inclined at asmall angle to the longitudinal axis C--C of the drill. The side cutters, 14b are housed and shrouded in suitable pockets on the periphery of the head (intermediate the milled grooves that receive the cutter block supports 76); and the lower shouldered ends of the tapered journal shafts i8b are threaded into the end Walls of these pockets. The upper cylindrical portions of the shafts are'fitted closely in reamed holes which hold them rigidly against lateral displacement; and the assembled parts are locked in position both by the lower edge of the upper section 15bwhich partly covers the ends of the shaft members 18h'- and also, if desired, by fusible metal seals SSL-33".

The complemental action of the two pair of .rolling cutter bits, 13b-13b and 14"-14b is essentially the same as that which characterizes the previously considered exemplifications of my invention. The teeth on the sides of the rolling cone members 13b act on the material at the center of the bore hole and cut a flat bottomed cavity whose diameter, g-g, is, in this case, about of the finished diameter a-a of the hole, and whose area is therefore about 50% of the completed section. The remainder of the material is removed from the annular zone, ca -g, by the curtate-cycloidal action of the projecting tooth elements on the rolling surfaces of the spindle cutters 14h-141. lower extremities of these elements overlap the zone of action covered by the roller bits 13b; andthe upper ends thereof are beveled off, as at 22h, to make an extended contact with the finished side wall of the bore hole; thus eliminating any sharp edges, or peripheral lines of rapid wear, on the cutting surfaces, and ensuring the efficient operation,

The

and the effective maintenance of the gauge diameter, of the tool for long continued periods of drilling in hard rock formation.

The organization shown in Figs. 4 and 5 is provided with a force feed lubricating system which is actuated and controlled by the revolution of one or more of the cutter bits; and which therefore corresponds, in functional character to the similarly actuated systems of the previously described constructions. In the third illustrative embodiment of my improvements the cutter actuated means for eecting the lubrication comprises; (1) a sleeve gear member 43b which is detachably secured to the upper end of one 0f the side roller cutters 14b (or to the adjacent extremity of the central bushing therefor) (2) an associated pinion 44b that is attached to the lower end of the pump shaft 45"; (3) the screw pump element 4Gb which is adapted to draw liquid from the cavity in which the cutter is revolving and discharge it into the lower end of the annular opening between the upper head section, 15b, and the central conduit 34h; and (4) the annular piston 41b which receives the liquid pressure established by the action of the pump 46b and transmits it tothe mass of lubricant above the said piston. The lubricant is discharged from the eXtreme upper end of the annular chamber in the section 15b through an opening 80 formed in a tube 80 that surrounds the conduit 34b and terminates at its lower end in a recess in the section 12b; from whence it is conducted to the bearings of the cutters 13b by ducts 39h-40b (see Figs. 5 and 6), and to the journal surfaces of the cutters 14h, by the passage ways 57b-58b (see Fig. 4). In this case the upper end of the annular cavity in the head is closed 01T from the flushing liquid by the centering plate, 81, the packing ring, 82, and the clamp nut and washer 83; but the plate 81 is provided with an aperture 84 through which the space above the piston 41b may be filled with lubricant when the head is disconnected from the drill stem 16", and the packing elements 82-83 are removed.

rlhe rate of feed to the bearings of the revolving cutters may be controlled entirely by the working pitch and the angular velocity of the screw pump 46h; but in order to guard against an excessive or undue accumulation of pressure in the liquid filled chamber below the piston I preferably provide a spring check valve 85 which may be adjusted to open at any desired pressure and permit of the escape of a portion of this liquid to the outside of the drill head.

The flushing liquid for the various cutter members is carried down through the central conduit 34" and is discharged from the lower end thereof through four inclined passage ways; two of which (38h-38h) deliver their streams against the rearward and upwardly moving sides of the cutters 13b-13b;

while the other two (S6-86) direct the issuing jets of liquid against the rearward and inwardly moving teeth of the side rolling bits 14-14. In all cases the flow is so directed that the tangential or oblique impingement of the water against the revolving cutter surfaces will effectually dislodge and wash away the material which is chipped out by the teeth, and keep the latter in clean and effec.- tive working condition.

It will now be obvious to those skilled in this art that the general features of my invention may be embodied in a large number of different forms of boring tool construction; and that certain features of these improvements-e. the system of cutter controlled lubricator feed-may be employed in conjunction with horizont-al and vertical disc drills, as well as with such types of roller bit tools as I have herein shown; or may be used with such associated types as are illustrated and described in my copending application Ser. No. 442,333 iiledFebruary 3rd, 1921.

That I claim as new and desire to secure by Letters Patent is:

1. In a rotary boring tool the combination of a head, a cutting member revolvably mounted thereon, a lubricant chamber, a piston located in said chamber for separating the lubricant contained therein from flushing water contained thereabove and a pump in the chamber' actuated by said cutting member for controlling the delivery of lubricant from said chamber to the bearings of said cutting member.

2. In a rotary boring tool the combination of a head, a cutting member revolvably mounted therein, a lubricant chamber associated therewith, a piston located within said lubricant chamber and separating the lubricant contained therein from flushing liquid contained therein, a pump in said chamber actuated by said cutting member for controlling the delivery of lubricant from said chamber and a check valve communicating with said chamber for limiting the edective pressure of said pump.

In testimony whereof, I have hereunto set my hand this 21st day of March, 1927.

FRANK L. O. VVADSWORTI-I. 

